Driving mechanism for vacuum electric furnaces

ABSTRACT

A driving mechanism is disclosed particularly for use in advancing work pieces in the interior of a vacuum furnace, the mechanism extending through the furnace wall for motor or manual driving from the exterior of the furnace, the mechanism being replaceable as a unit, having provisions for sealing against fluid leakage and for reduction of heat conductivity between hot and cold locations, for liquid cooling at intermediate locations and for effective heat conductivity at cool locations. Provisions are also made for easy separation if desired of portions subjected to seizure at high heat levels, and for evacuation of interior portions subjected to vacuum.

United States Patent [191 Kreider et al.

DRIVING MECHANISM FOR VACUUM ELECTRIC FURNACES Inventors: Benjamin A. Kreider, Richboro;

William J. Matalsky, Warminster, both of Pa.

US. Cl 1. 432/121, 13/31, 432/205 Int. Cl. F27b 9/14, F27b 11/08 Field of Search 432/205, 121, 122; 13/31 References Cited UNITED STATES PATENTS l/l963 Palmer 432/205 6/1973 Kreider et al 13/31 [4 1 Nov. 12, 1974 Primary Examinerlohn J. Camby Attorney, Agent, or Firm-Zachary T. Wobensmith, 2nd; Zachary T. Wobensmith, lll

[57] ABSTRACT A driving mechanism is disclosed particularly for use in advancing work pieces in the interior of a vacuum furnace, the mechanism extending through the furnace wall for motor or manual driving from the exterior of the furnace, the mechanism being replaceable as a unit, having provisions for sealing against fluid leakage and for reduction of heat conductivity between hot and cold locations, for liquid cooling at intermediate locations and for effective heat conductivity at cool locations. Provisions are also made for easy separation if desired of portions subjected to seizure at high heat levels, and for evacuation of interior portions subjected to vacuum.

14 Claims, 6 Drawing Figures FURNACES BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to .driving mechanisms particularly adapted for use with vacuum electric furnaces.

2. Description of the Prior Art Furnaces have heretofore been proposed in which the work pieces are advanced through a plurality of treating zones.

Various provisions have been made for advancing the work pieces, such as on wheeled trucks as in the US. Pats. to Kugel, No. 802,517, and Borner, Nos. 3,583.,690 and 3,625,496, and Austin, et al., British Pat. No. 565,104.

It has also been proposed to employ endless chains to advance'the work pieces as in the U.S. Pat. to Kochendorfer, No. 1,252,813, and to employ overhead trackways for movable elements such as in the US. Pats. to Miskella, No. 2,814,684, and Oetjen, et al., No. 3,192,645;

Bielefeldt, in US. Pat. No. 3,609,295 shows a vacuum electric furnace in which carriers of open rectangular frames are provided for the work pieces carried on a narrow bar having transverse horizontal axles with small rollers movable along interior tracks. The bars are driven by dogs on an endless chain within the vessel, the chains being driven by an exteriorly disposed motor.

Where the temperature gradient between the interior and exterior of the furnace is not great the provision of driving mechanism having portions extending through the furnace wall does not present great difficulties. The same is true where the interior vacuum is not high.

In vacuum furnaces, where the interior temperatures are of the order of 800 F. or higher, and the vacuum is of the order of inches or less of mercury, serious problems arise. The interior temperatures are too high to permit of using driving motors inside the furnace. The provisions heretofore made for driving shafts extending through the furnace wall and driven by an external power source,have not proven satisfactory because of vacuum leakage, excessive-heat leakage, early failure of parts exposed to high temperatures or for other reasons. v

SUMMARY OF THE INVENTION In accordance with the invention driving mechanism is provided, suitable particularly for vacuum electric furnaces, which functions satisfactorily over the temperature gradient between starting up and operation and with the temperature gradient between the interior and exterior of the furnace in operation, which is avail able as a cartridge type unit for quick replacement, in which the components subjected to high temperatures can be readily removed if desired, which has low heat conductivity between hot and cold locations, which has high heat conductivity of the portions at lower temperatures, in which seals are provided to prevent vacuum leakage and the, seals are protected by cooling to increase their useful life, in which the interior parts subjected to vacuum can be readily evacuated, and which is normally motor driven but can be manually actuated, if desired. g

It is the principal object of the invention to provide driving mechanism which is particularly suitable for adbars 29 which vancing work pieces through a vacuum electric furnace.

It is a further object of the invention to provide driving mechanism as aforesaid which will have freedom from operating problems, a long useful life and which can be readily replaced, if desired.

Other objects and advantageous features of the invention will be apparent from the description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS The nature and characteristic features of the invention will be more readily understood from the following description taken in connection with the accompanying drawings forming part hereof, in which:

FIG. 1 is a fragmentary vertical sectional view of a portion of the hot zone of a vacuum-electric furnace having the driving mechanism of the invention mounted thereon;

FIG. 2 is an enlarged fragmentary vertical sectional view of the driving mechanism;

FIG. 3 is a fragmentary elevational view showing the exterior driving motor and the provisions for manual actuation;

FIG. 4 is an end elevational view taken from the location 44 of FIG. 2;

FIG. 5 is a vertical sectional view, enlarged, taken approximately on the line 5-5 of FIG. 2; and

FIG. 6 is a vertical sectional view taken approximately on the line 6-6 of FIG. 2.

It should, of course, be understood that the description and drawings herein are illustrative merely and that various modifications and changes can be made in the structure disclosed without departing from the spirit of the invention.

Like numerals refer to like parts throughout the several views DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularly to the drawings, a fragmentary portion of the hot zone of a vacuum furnace is shown which includes a furnace tank wall 10 with a surrounding jacket wall 11, the space 12 therebetween providing for cooling liquid circulation.

Within the interior of the tank wall 10, and spaced inwardly therefrom, a plurality of spaced reflective shields 14 are shown, supported from a shield support ring 15 and which in turn support resistance heating elements 16 in strip or sheet form. The shields 14 and heating elements 16 can be of any desired type and if desired could be similar to those described in the application of Cyrway, et al., filed July 5, 1973, Ser. No. 376,538, now US. Pat. No. 3,812,276.

Supporting brackets 20, secured to the tank wall 10 and extending through suitable openings in the shields 14 and heating elements 16 carry spaced elongated rails 22. I

Load carriers 25 are provided having spaced elongated side frame bars 26', with spaced transverse rods 27 secured thereto. A selected number of the rods 27 can extend beyond the side frame bars, as at'27a to carry track engaging rollers 28. The rollers 28 ride on the tops of the rails 22 and are retained by outer flange aid in retaining the carriers 25 on the rails 22.

The rods 27 between the frame bars 26 have rollers 30 which rollers 30 and their supporting rods 27 can be spaced at any desired locations but are preferably spaced to function as a rack for engagement by the teeth of a driving sprocket 33.

The carriers 25, at spaced locations, and preferably at their connections with other aligned carriers 25 can support pendant brackets 31 which carry the work pieces. The rails 22, and their supports, and the carriers 25 can be of any desired type but advantageously can be as described in the application of Kreider, filed Apr. 22, 1974. Ser. No. 462,961.

The tank wall 10, at desired locations, is preferably provided with a mounting cylinder 35 in fluid tight relation which has a mounting flange 36 carried thereon for detachably supporting the driving unit to be described.

The driving unit has a mounting flange 38 which is secured to the flange 36 in any desired manner, such as by bolts 39, and with an interposed packing 40 to preventfluid leakage at this location.

The mounting flange 38 has a cylindrical housing 41 fixedly secured thereto which is surrounded, in spaced relation, by a cylindrical jacket 42. The space 43 between the housing 41 and jacket 42 provide-s for cooling fluid circulation and has a cooling liquid supply pipe 44 connected thereto by a passageway 45 in the thereto for rotation therewith. The discs 78 substan-- flange 38 and a discharge passageway 46 in the flange 38 connected to a cooling liquid discharge pipe 47.

i The housing 41 has mounted therein, in spaced relation, a pair of shaft bearings 49carrying the drive shaft 50, a sealing and lubricating fluid space 51 being provided between the housing 41 and the shaft 50.

The outer end of the space 51 is closed by an outer end closure plate 52 held in engagement with a closure ring 56 secured to the housing 51 by bolts 53. A seal 54, such as an O-ring, prevents fluid leakage at this location and a shaft seal 55 ofconventional type, suchas a garter spring oil seal is provided between the closure plate 52 and the shaft 50.

The inner end of the space 5l'is-closed by an inner end closure plate 57 held in position by bolts 58 extending through the closure plate 57 and into a closure ring59 engaged with the housing 41 and secured to the jacket 42 as by welding. 1

A packing 55 is interposed between the shaft and the inner end closure plate 57 similar to the packing previously referred to.

The space 51 has a drain plug 61 in the housing 41 and has a transparent supply receptacle 62 and a supply pipe 63 connected thereto for the supply of lubricating, sealing and heattr'ansferring fluid and observation of the level of the-fluid. h

The shaft 50 has a hollow interior 51a which extends inwardly beyond the inner bearing 49 and packing 55 and is closed at its outer end by. a plug 65 which has i mounted thereon and keyed'thereto a pinion 66.

' ing liquid supply pipe for supplying liquid through the plug 65. The union 69 has a non-rotating siphon pipe 71 extending into the interior of the shaft 50 for the return of coolingliquid therethrough and to a fixed discharge pipe 72.

The shaft 50 is preferably of a material, such as carbon steel, having good heat conductive properties to aid in cooling.

The shaft 50 has a hollow tubular shaft extension 75 connected thereto by an interposed connector 76, welded to the shaft 50 and shaft extension 75 by vacuum tight welds. I

The shaft extension 75 can be of any desired material, but is preferably of a material, suchas stainless steel, having relatively poor heat conductive properties and has a minimal cross section of adequate strength. This serves to reduce the amount of heat transmitted to the inner packing 52 and inner bearing 49 and reduces the burden on the cooling provisions for the shaft 50 and associated structure. v

The interior of the shaft extension 75 is preferably in communication with the exterior through a plurality of openings 77 for rapid evacuation when the furnace chamber is evacuated.

The connector76, on the exterior thereof, has a plurality of shield discs 78 of reflective metal secured tially close the inner end of the mounting cylinder 35 against radiant energy transmission outwardly therethrough. 1

The shaft extension 75 is closed at its inner end by a sprocket connector 80, has an end portion 81 extending into and secured to the shaft extension 75 and has a rim portion 82 with radial slots 83 open at their outer ends and with relief cut-outs 84 inwardly of each of the slots 83.

The sprocket 33 preferably has a central rectangular opening 85 for engagement on a square shaft end portion 86 on the sprocket connector'80. The sprocket 33 is held in position by bolts 87 carrying nuts 87a, the heads of bolts 87 being in counterbores 88 and the shanks engaged in the radial slots 83. The engagement of the bolts 87 in this manner permits of shearing'of the shaft, 50. For normal furnace operation the shaft 50 may run at about 20 r.p.m. to advance the work pieces bolts 87 for replacement in the event of undesired seizure, the radial slots permitting fall out or easy removal. i

The pinion 66 preferably has a sprocket chain engaged therewith, the chain 95 being carried on a sprocket 96 on a shaft 97 normally driven by a motor 98 on the exterior of the wall 10 of the furnace-tank. The outer end of the shaft 97 is preferably hexagonal, as at 99, for the reception of a wrench (not shown) for tuming'the shaft 97 and through the sprocket 96, chain 95 and pinion 66 to manually operate the shaft 6.6 if the motor 98 is for any reasonout'of action.

Themode of operation will now be pointed out.

1-ln operation the temperature in the interior of the i furnace may be of the order of l,200 F. with starting up and exterior temperatures at normal atmospheric levels. The increase of temperature within the furnace at the'desired rate. The structure disclosed is not howfor a leak to occur it would have to pass the outer seal 55, the main body of liquid in the space 51 and the inner seal 55. This liquid also serves as a heat transfer agent to the outer and inner cooling fluids.

The exterior of the housing 41 is cooled by the cooling liquid supplied at the supply connection 44 and passing through the space 43 for discharge through the discharge connection 47.

The cooling fluid supplied through the supply pipe 70 through the coupling or union 69 to the interior of the shaft 50 is effective for cooling the seals 55, and the bearings 49, and particularly the inner seal 55 and bearing 49, the siphon pipe 71 delivering the liquid to the discharge pipe 72.

Upon evacuation of the interior of the furnace tank within the wall the openings 77 are effective for evacuation of the interior of the shaft extension 75 thereby avoiding slow contamination of the interior of the furnace which might occur if free evacuation were not available.

Manual operation of the shaft 50 can also be effected if desired as heretofore pointed out.

We claim:

1. Driving mechanism for use with a vessel having the interior and exterior subject to temperature and pressure differentials comprising a fixedly mounted housing facing the interior of the vessel,

a shaft journaled within said housing in spaced relation thereto for rotation with respect to said housing, and

liquid sealing means interposed between said shaft and said housing for preventing fluid leakage between the interior and the exterior of the vessel and comprising sealing members spaced along said shaft in sealing relation thereto, and

a liquid supply connection communicating with the space between said shaft and said housing for supplying lubricating and sealing liquid between said sealing members.

2. Driving mechanisms as defined in claim 1 in which members are provided for supplying cooling fluid in cooling relation to said shaft and for-removal of said cooling fluid.

3. Driving mechanism as defined in claim 1 in which said shaft has a hollow interior portion, and

members are provided for supplying cooling fluid to the interior portion of said shaft and for removal of said cooling fluid.

4. Driving mechanism as defined in claim 1 in which said shaft has an extension portion within the vessel,

and

said extension portion is of a material of lesser heat conductivity than the portion of said shaft contiguous to the vessel wall.

5. Driving mechanism as defined in claim 1 in which said shaft has an extension portion within the vessel,

and

said extension portion is of reduced cross section for minimizing heat conduction therealong.

6. Driving mechanism as defined in claim 1 in which said shaft has a hollow tubular extension within said vessel, and

vents are provided communicating with the interior of said hollow tubular extension for evacuation thereof.

7. Driving mechanism as defined in claim 6 in which said tubular extension is closed at its inner end by a connector, and

said connector has a polygonal end portion for the reception of a driven member.

8. Driving mechanism as defined in claim 7 in which said driven member is a sprocket with a central opening complemental to said polygonal end portion. 9. Driving mechanism asdefined in claim 8 in which said hollow portion of said shaft extends inwardly contiguous to at least one of said sealing members for cooling said sealing member.

12. Driving mechanism as defined in claim 1 in which operating means is providedfor rotating said shaft including a motor connected in driving relation to said shaft, and

said operating means includes a manually accessible portion for manual operation of said shaft independent of said motor.

13. Driving mechanism as defined in claim 10 in which said shaft has a hollow interior portion, and

sail last mentioned members include fluid connections for supplying cooling fluid to the interior portion of said shaft.

14. Driving mechanism as defined in claim 1 in which the wall of said vessel is provided with a mounting member the interior of which is in communication with the interior of the vessel,

said housing is detachably connected to said mounting member, and.

said shaft has heat shielding members carried thereon for blocking access of radiant heat to the interior of said mounting member.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patenr-No- 3,847 539 Dated Novembet'lZ, 1974 Inventor(s) Benjamin A. Kreider, William J. Metalsky It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In .the heading, the riame of the second inventor-should appear as William J. Metalsky Signed and sealed this 7th day of January .1975.

" (SEAL) Attest;

MCCOY M, GIBSONJR. c. MARSHALL DANE Attesting Officers Commissioner of" ,Pater 1ts FORM PC3-1050 (10-69) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECT IQN Patent'No. 3 347 539 Dated November-12, 1974 Inventor(s) Benjamin A. Kreide r, William J. Metalsky It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Inthe headirig, the riame of the second v inventor-should appear as William J. Metalsky Signed and sealed this 7th day of "January: 1975'.

' (SEAL) Attest: V e

' MCCOY M. GIBSON'JR. c. MARSHALL DANN Attestihg Officer 7 Commissionerof'iPatents F ORM PC1-1050 (10-59) 

1. Driving mechanism for use with a vessel having the interior and exterior subject to temperature and pressure differentials comprising a fixedly mounted housing facing the interior of the vessel, a shaft journaled within said housing in spaced relation thereto for rotation with respect to said housing, and liquid sealing means interposed between said shaft and said housing for preventing fluid leakage between tHe interior and the exterior of the vessel and comprising sealing members spaced along said shaft in sealing relation thereto, and a liquid supply connection communicating with the space between said shaft and said housing for supplying lubricating and sealing liquid between said sealing members.
 2. Driving mechanisms as defined in claim 1 in which members are provided for supplying cooling fluid in cooling relation to said shaft and for removal of said cooling fluid.
 3. Driving mechanism as defined in claim 1 in which said shaft has a hollow interior portion, and members are provided for supplying cooling fluid to the interior portion of said shaft and for removal of said cooling fluid.
 4. Driving mechanism as defined in claim 1 in which said shaft has an extension portion within the vessel, and said extension portion is of a material of lesser heat conductivity than the portion of said shaft contiguous to the vessel wall.
 5. Driving mechanism as defined in claim 1 in which said shaft has an extension portion within the vessel, and said extension portion is of reduced cross section for minimizing heat conduction therealong.
 6. Driving mechanism as defined in claim 1 in which said shaft has a hollow tubular extension within said vessel, and vents are provided communicating with the interior of said hollow tubular extension for evacuation thereof.
 7. Driving mechanism as defined in claim 6 in which said tubular extension is closed at its inner end by a connector, and said connector has a polygonal end portion for the reception of a driven member.
 8. Driving mechanism as defined in claim 7 in which said driven member is a sprocket with a central opening complemental to said polygonal end portion.
 9. Driving mechanism as defined in claim 8 in which said connector has radial open ended slots, and attaching members for said sprocket are provided comprising bolts engaging said sprocket and extending in intersecting relation to said slots.
 10. Driving mechanism as defined in claim 2 in which said housing has a jacket in spaced surrounding relation thereto, and said last mentioned members include fluid connections for supplying cooling fluid between said housing and said jacket.
 11. Driving mechanism as defined in claim 3 in which said hollow portion of said shaft extends inwardly contiguous to at least one of said sealing members for cooling said sealing member.
 12. Driving mechanism as defined in claim 1 in which operating means is provided for rotating said shaft including a motor connected in driving relation to said shaft, and said operating means includes a manually accessible portion for manual operation of said shaft independent of said motor.
 13. Driving mechanism as defined in claim 10 in which said shaft has a hollow interior portion, and sail last mentioned members include fluid connections for supplying cooling fluid to the interior portion of said shaft.
 14. Driving mechanism as defined in claim 1 in which the wall of said vessel is provided with a mounting member the interior of which is in communication with the interior of the vessel, said housing is detachably connected to said mounting member, and said shaft has heat shielding members carried thereon for blocking access of radiant heat to the interior of said mounting member. 